Add equivalent of "hover" for touch displays

**What is the current behaviour and why should it be changed?**

On desktop builds, hovering the mouse over the channel user displays their profile details in a tool tip:

As no "hover" action is available for touch displays (e.g. Android), this feature is unavailable.

**Describe possible approaches**

A single tap or, probably better, long-hold could be used to display tool tips in general. (Long-hold would avoid misinterpretation of single tap on a checkbox or menu, etc.)

I'm guessing touch screens also are missing right-click "What's this?" support. Possibly that could be implemented as above, with "Show musician profile" as an extra option where applicable.

Other trigger actions could be double tap or two-finger tap. Long-hold is prefered, I think.

**Has this feature been discussed and generally agreed?**

Only with my partner, who raised it.

Empieza localizando el tooltip de hover de escritorio para los usuarios del canal y el comportamiento de «What's this?» al hacer clic derecho; después, revisa cómo se gestiona la entrada táctil. El issue necesita un gesto acordado y debe considerarse terminado cuando una interacción táctil muestre el tooltip relevante o el perfil del músico sin interpretar erróneamente los taps en los controles.

Escrito por el modelo de indexación a partir del texto del issue.